This protocol will evaluate the antitumor activity of melphalan (L-PAM) with L-buthionine sulfoximine (BSO) in patents with recurrent or persistent ovarian cancer. The effect of BSO pretreatment on glutathione (GSH) metabolism in peripheral blood lymphocytes and tumor issue, as well as BSO pharmacodynamics will be studied. This protocol is designed to meet five objectives. These objectives are as follows: (1) To measure the activity (response rate, time to progression, and response duration) of intravenous L-PAM with BSO in patents (a) with ovarian cancer refractory to a taxol/platinum combination in Phase II trial and (b) who have failed at least one chemotherapy regimen and may or may not have received prior radiotherapy. (2) To describe the relationship between glutathione depletion by BSO in peripheral mononuclear cells (PMN) and the activity and toxicity of the combined treatment as a possible predictor of toxicity and/or response in this population. (3) To verify the degree of GSH depletion by BSO in ovarian tumor cells in a cohort of patients with refractory ovarian cancer. (4) To relate depletion of tumor GSH by BSO to changes PMN GSH, and to gamma-glutamylcysteine synthetase (gamma-GCS) expression. (5) To further characterize L-PAM pharmacokinetics following BSO treatment.